
Op is easy to manipulate

Exactly. He doesn’t know how to trust. But at the same time he knows that he won’t be able to survive if he doesn’t learn how to. It’s not his fault if he trusts and places his faith in the wrong people. At least he’s trying to live normally despite everything. On another note, people have to remember that this story is from the perspective of Sunwoo. So what we’re seeing of the other characters could be fragments of his own biases and misconceptions. Things that may seem like red flags may actually be imaginations in his head that are disproportionate to what is actually happening around him, stemming from his severe trauma and inability to trust. But then again, it might be the other way around and he’s actually getting manipulated. We don’t know.
He’s a freak